Guitar Hero appears to be taking over the world - well at least the US. The series is so popular that it's moved beyond home consoles and PC to the DS. In what must rank as one of the most ambitious releases the DS has seen, Guitar Hero: On Tour attempts to bring the Guitar Hero experience to the handheld, complete with extravagant fret add-on and guitar pick. Is it the same awesome experience that you get with a plastic guitar in your hands or an idea that should have stayed in the concepts department?

Much of this rests on the fret add-on, bundled with every copy of the game and required in order to play. This plugs into the GBA port on your DS, enabling you to hold the handheld somewhat like a book with your left hand on the fret buttons - of which there are only four. This is the first compromise that has had to be made in bringing the series over to the DS. For hardcore fans it's a big deal, but hardcore fans probably aren't the DS game's biggest audience. For newcomers who are playing Guitar Hero for the first time it's not a big problem and the difficulty levels ramp up well as you move from beginner, through medium to hard and expert.

Sadly other issues that do cause problems are present. When your hand is strapped in to the fret add-on you have very little finger dexterity, making the game rather uncomfortable to play. You only really need to be able to move them slightly as there's no need to move them from their positions directly above each button, but it just doesn't feel right. The set-up with the game being played with the DS like a book also feels quite unnatural. The add-on also tends to move around a fair bit, and becomes so loose at times that the game lost connection to it. It didn't happen often, but enough to be an annoyance.

For the strumming the game comes with a mini stylus shaped like a pick which you use to strum on the DS touch screen. In theory it sounds like a good idea, but in practice it's far from perfect. You want to be able to keep the stylus held to the screen and just move it back and forth, but that doesn't work. Simply tapping the screen doesn't work either. You need to tap and slide in order to guarantee that the game will register a strum. It makes for a control system that never feels solid and reliable. You do eventually settle into a groove, but out of the blue the game will fail to recognise a strum and your high score attempt is ruined.

The whammy bar hasn't been strapped onto the add-on, but it's included in the game via the touch screen. When you're playing a sustained note you can flick the pick stylus back and forth as if it were a whammy bar, scoring you more points in the process. With neither the DS nor the add-on including any form of motion sensor star power, activated by raising the head of the guitar in the air in the home console games, this has had to be reworked too. On the DS you achieve the ability to activate star power in the same way (hitting a series of special notes) but you activate it by shouting into the microphone. It works, but perhaps a little too well. If there's a relatively loud noise near you the DS microphone will pick it up and activate star power, doubling your multiplier whether you wanted to or not.

Duels are interesting, but no online play hurts.

Career mode is similar to what's been seen in previous Guitar Hero games, with you working through sets of four songs and an encore song, with a total of 26 available to unlock. 26 songs is certainly far less than what you get on a DVD in the home console games and the sound quality, through the speakers or through headphones, isn't great. It's acceptable and understandable given the size limitations of a DS cart compared to a DVD, but still a disappointment. If you're having trouble completing a certain song on a higher difficulty the included practice mode lets you tackle them without having to worry about scoring.

By far the most original game mode in GH: On Tour is the power-up heavy guitar duel. Here you can play against an AI or human opponent (local wi-fi only, no online). By successfully playing through a series of notes you'll be given a power-up to use against your opponent, which are themed around being a rock star. For example, you can set fire to your opponent's screen because you're rocking so hard, or get a fan to demand an autograph. Other power-ups just screw with your performance, like the screen switch, which swaps over the two screens. It's a fun mode, but without online support you'll have to hunt down other local owners if you want to play head to head.

As entertaining as that is, it's hard to recommend it over multiplayer with one of the already available home console games. With a more reliable control system Guitar Hero: On Tour would have been a perfectly playable, enjoyable game, but with its problems it feels more like a novelty. Getting the game to work on the DS is admirable and technically a solid achievement, but it doesn't make for a must-own DS title.